A self-propelled twin anti-aircraft gun acquired from the Soviet Union in 1961. The armament is the same as in the towed S-60 (57 ItK/60) cannon, calibre 57 mm. The carriage is a modified chassis of the T-54 tank, with four twin road wheels per side instead of five. The analogue calculator is similar to the one used in the  ZU-23-2 (23 ItK/61).

The performance of the weapon system was improved in the late 1960s with the installation of a more reliable radio system to replace the original Soviet radio equipment. Already at that time it was suggested that this weapon system should be phased out by the end of the 1970s. However, after the purchase of the  ZU 23-2 or in Finnish service the 23 ItK/61 “Sergei”, a decision was made to retain the system in service.

In the early 1990s, the Defence Forces acquired more of these tanks and spares from Hungary, which was significantly reducing the size of its armed forces post-1989. The additional vehicles arrived in Finland by 1993. The aim was to modernise the system in the same way as the 23 ItK/61 cannons, by installing, among other updates, electronic calculators and sighting systems, as well as night vision equipment. However, the project proved too expensive, so the 57 ItPsv SU-57 vehicles were decommissioned in 2006.

SPECIFICATIONS:

• calibre 57 mm
• muzzle velocity 1400 m/s
• effective range 4000 m
• rate of fire 120 rounds per minute per gun
• traverse rate 2–22 degrees per second
• weight 28,100 kg
• impact-fuzed shell
• on-board ammunition 316 rounds
• diesel engine 520 hp
• maximum speed (road) 50 km/h
• fuel capacity 812 + 400 litres
• fuel consumption 190 litres per 100 km
• gears 5 forward, 1 reverse

References: E-mail interview of Curator of Parola Armour Museum, July 2020; Palmu Pentti, Yön Yli Päivään – Suomen ilmatorjunnan vaiheita 1925–1990, Ilmatorjuntaupseeriyhdistys Ry, 1989; Archives of the Anti-Aircraft Museum